1. Field of the Invention.
The invention relates to a rifled slug type of gun-barrel projectile.
2. Description of Related Art.
This type of gun-barrel projectile is described in EP 0 341 543 B1. The upper part of the end part of this projectile is formed as a solid body. It has a slight radial expansion vis-à-vis the blind hole of in the lead head, so that it has to be inserted into it using a force. Then, at a plurality of locations on the periphery of the lead head, preferably at three places distributed uniformly on the periphery of the lead head, lead is driven pointwise radially inwardly, where the displaced lead flows into a peripheral groove of the upper part of the end part. This inward displacement of lead occurs using rod-shaped steel pins similar to a punched-in part. In virtue of the force fit of the upper part of the end part in the lead head and the pointwise incorporation of the lead in the upper part of the end part, the latter can be joined captively with the lead head.
In the case of this prior art gun-barrel projectile a predetermined breaking point is arranged between the rod-like central part and the piston-like bottom part of the end part, said breaking point being obtained at the time of manufacture in an injection molding process by insertion of a metal sleeve into the mold. This manufacturing process is relatively costly and prolongs the cycle time at the time of manufacture. A further drawback is the fact that the predetermined breaking point cannot be configured very uniformly. This has negative effects on the internal and external ballistics of the projectile.
In the evolution of firing the piston-like end part shifts upwards on the rod-like central part after detachment of the predetermined breaking point, until its upper side contacts the underside of the upper part. A barblike projection encircling the rod-like central part holds the end part on the central part thus preventing the central part from detaching itself rearwardly from the rod-like central during the flight phase of the projectile. During the flight phase the rear end of the rod-like central part projects rearwardly from the piston-like end part. This is a drawback for the external ballistics of the projectile, because of the flow conditions resulting therefrom in the posterior zone of the rear part. Also disadvantageous in this respect is the fact that the rearwardly projecting end of the rod-shaped central part is non-uniform in its external form because of the manufacturing process described.
In the hereinbefore described gun-barrel projectile a very good damping of the gas pressure increase is noted in the barrel. Nevertheless the predetermined breaking point rends after firing because of the relatively large tolerances from cartridge to cartridge caused by the manufacturing process at relatively widely differing gas pressures. This has effects on the further pressure development in the barrel and consequently on the exit velocity of the projectile. Accordingly, it leaves the barrel from firing to firing with relatively widely varying velocity, whereby target precision suffers.